Defense Secretary Chuck Hagel speaks at the National Defense University at Ft. McNair in Washington on April 3. / Alex Wong Getty Images

by Tom Vanden Brook and Jim Michaels, USA TODAY

by Tom Vanden Brook and Jim Michaels, USA TODAY

WASHINGTON - The Pentagon budget proposed by President Obama on Wednesday will assume that the automatic spending cuts that started March 1 will end and will contain no long-term reductions in troop levels beyond those already in motion, according to congressional sources.

Three aides on Capitol Hill who are not authorized to speak on the record about the budget, which will be released Wednesday, said the Army and Marine Corps plan to continue to thin their ranks over the next five years to reach targets of 490,000 soldiers and 182,100 Marines.

The Army has about 560,000 active-duty personnel now, while the Marines have about 197,000. The reduction was set in motion last year to accommodate the $487 billion reduction in Pentagon spending over the next decade.

Military leaders, starting with Defense Secretary Chuck Hagel and his predecessor, Leon Panetta, said the sequestration cuts could hollow out the military and leave the nation unable to meet its defense needs. Hagel said last week that the Pentagon will have to make serious cuts in personnel and other programs if the sequester stays in effect.

Sequestration will require about $500 billion in cuts from the Pentagon, including about $40 billion this year.

"The president's budget will replace the sequester, which was designed to be bad policy for everyone," White House press secretary Jay Carney said Tuesday.

Republicans, who control the House, have criticized Obama's budget before its release. House Republicans have passed their own budget, which includes sequestration cuts for non-defense items and higher defense spending, while the Senate passed a Democratic plan last month that included $240 billion in spending cuts over 10 years but did not specify troop levels.

The budgets produced by the Republicans and Democrats are "not to be believed," said Thomas Donnelly, a defense analyst at the American Enterprise Institute. There is little reason to believe sequestration will be solved soon, making it likely that steep cuts in troop levels will occur. Moreover, about 50,000 troops are funded by supplemental war-spending budgets that will diminish with the withdrawal from Afghanistan, he said.

"There was no other way to do this budget. What alternative to the previous plan could they come up with, in the time allotted, with ongoing White House-congressional negotiations and the possibility of continued GOP unwillingness to give on taxes?" says Michael O'Hanlon, defense expert at the Brookings Institution.

Last year, Gen. Raymond Odierno, the Army chief of staff, said his service could remain ready to fight with 490,000 soldiers if it had several years to implement the change.

The Army dropped to a low of 479,000 soldiers in 1999, Pentagon records show, but increases caused by the demands of fighting simultaneous wars in Iraq and Afghanistan led Congress and the Bush administration to call for an increase that peaked at 566,000 soldiers in 2010.

The Marines bottomed out in 1950, the first year of the Korean War, 74,000 Marines. That number jumped to 193,000 the following year and has never dipped below 173,000 since then.

Since the end of World War II in 1945, the military has seen significant fluctuations in troop levels, Pentagon records show. The Army reached 1,596,000 soldiers in 1952 and 1,570,000 in 1968, the peak years for the wars in Korea and Vietnam. Between those wars, the Army bottomed out at 859,000 soldiers in 1961. The Army's post-Vietnam peak came last in 1987, when it had 781,000 soldiers, records show.